Can I use 12V DC for the power supply using LM371 on Tonepad ?

[sam_801023]

Can I use 12V DC for the power supply using LM371 on Tonepad ?
Hi, everyone, this is my first post here.

I am going to build the tonepad's PSU using LM317
However, I want to use 12V DC for the input of the PSU and deliver a clean 9V DC, can I do so ?

Also, if I do so, the negative side of 12V DC input should be connected to the ground, which is the same ground of the ouput power.
Am I right ?

Sorry for my poor English

[WLS]

I don't see why a LM371 could not achive the results your looking for.

Personally, I would use a fixed regulater instead  of an adjustable one.

But, that would be me.

On most projects the negative side is ground. The only time you need to be concerned with this would be in a positive ground circuit.

[.Mike]

Hi sam,

To further what WLS said, if you want the output to be fixed at 9V DC, you could use either a 78L09 (<100mA) or a 7809 (<1A). That way, the minimum components you would need would be the regulator and two capacitors. You could easily build it on perfboard and save the money on the PCB.

The 78L09, like this one (datasheet), will output 9V DC if provided any DC voltage between 11V and 30V. The 7809, like this one (datasheet), will output 9V DC if provided any DC voltage between 11V and 35V.

See Figure 7 in the second datasheet I linked to for a schematic. It is as simple as can be.



Mike

[waltk]

Hi Sam,

I also like the suggestion to use a fixed regulator, but if you really want to use the Tonepad layout, you can.  Because you are using a 12V DC input, you can omit the transformer, the first 4 diodes (that form a rectifier for the AC output from the transformer), and the two large capacitors.  I've done this using the Tonepad layout, and it works fine.

[sam_801023]

Thanks for all reply, there is another question left.

When I use 12VDC as the input power, as there should be 2 wire from the input DC power, one is positive, one is negative.

Should I directly connect the negative wire of the input DC power to the ground of the regulator circuit, which means the same ground for input and output DC power ?

Sorry for my poor English.

[waltk]

When I use 12VDC as the input power, as there should be 2 wire from the input DC power, one is positive, one is negative.

Should I directly connect the negative wire of the input DC power to the ground of the regulator circuit, which means the same ground for input and output DC power ?

Yes.  All ground points in the circuit are connected to the negative input and negative output.